ECDC risk assessment: the risk of vCJD transmission via blood and PDMPs manufactured from donations obtained in the UK

The European Centre for Disease Prevention and Control (ECDC) has published a risk assessment on the risk of variant Creutzfeldt-Jakob disease (vCJD) transmission via blood and plasma-derived medicinal products (PDMPs), manufactured from donations obtained in the UK.

In February 2021, the UK lifted its ban on the use of UK-sourced plasma to produce immunoglobulin products. Taking into consideration a risk-benefit analysis, the UK assessed the vCJD risk for immunoglobulin products manufactured from UK plasma as very low, and acceptable in the context of overall vCJD risk in the general population. The presence of transmissible proteinaceous infectious particles, called prions (PrPSc), have been linked to vCJD among asymptomatic blood and plasma donors.

The ECDC report that the prevalence of vCJD-related PrPSc in the UK blood donor population is likely to broadly mirror the prevalence in the UK population as a whole. Evidence from retrospective cohort studies, using peripheral lymphoid tissue, suggests that the underlying prevalence of people that may be in the vCJD carrier state is around 0.05%, although there remains uncertainty around this estimate. The contrast between the estimated prevalence of vCJD-related PrPSc and the reported number of clinical vCJD cases seen to date, suggests that those in whom PrPSc is detected through an antemortem lymphoid tissue survey may never develop any symptoms of prion disease. Further uncertainty exists regarding the extent to which individuals who may be carrying PrPSc as latent or subclinical vCJD infection are capable of transmitting the infection to others, including through donation of blood and blood products.

The vCJD infection risk from the donations and final products is decreased by the safety measures implemented to reduce the risk of donation by exposed donors, and during whole blood processing or plasma fractionation. However, the ECDC find that absence of a reliable diagnostic blood test makes it difficult to assess the residual risk for transmission of vCJD infection through blood components and PDMPs obtained from UK-sourced blood and plasma donations with any degree of confidence.

Source: ECDC, 3 August 2021